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Views: 0 Author: Site Editor Publish Time: 2021-04-16 Origin: Site
There are many types and styles of ceramic tableware on the market, and consumers have a wide range of choices. However, the quality of ceramic tableware often varies from good to bad, which creates problems for consumers in choosing ceramic tableware. So how to choose a safe ceramic tableware requires us to understand the production process and raw materials of ceramic tableware.
The production process of ceramic tableware generally includes: ceramic embryo making, glazing, kiln firing and painting. The raw materials are mainly clay, glaze (glaze) and color (painting material).
The clay is generally kaolin or clay, which is natural clay or minerals without chemical addition, so it is basically safe.
The presence of glaze makes the surface of ceramics smooth and glassy. It is made by grinding mineral raw materials (feldspar, quartz, talc, kaolin, etc.) and raw materials in a certain proportion (some raw materials can be made into frit first). The glaze slurry is applied to the surface of the body and calcined at a certain temperature. From the perspective of the raw materials of the glaze, the transparent glaze is non-toxic and harmless. Some colored glazes are added with a certain compound, and different glazes have different colors. For example, the addition of cadmium compounds shows red or yellow. The colored glaze contains a certain amount of heavy metals, and these heavy metal elements will not remain after high temperature treatment (about 1200 degrees Celsius), so high-temperature fired ceramic tableware should be selected.
The "color" of ceramic tableware is generally chemical materials, especially low-cost, which may contain heavy metal elements such as lead and cadmium. According to the firing process of ceramics, it can be divided into underglaze, in-glaze and overglaze.
1) The underglaze color is made by using pigments to paint patterns on the plain or green body, then cover the glaze described above, and fire it at high temperature (1060℃~1250℃). The underglaze color surface is bright, smooth and not protruding, and has strong mechanical wear performance and corrosion resistance. At the same time, the "color" is covered under the glaze to prevent the precipitation of heavy metals in the "color", which is relatively safe.
2) In-glaze color is to use a high-temperature fast-fired ceramic pigment to paint on the white-glazed porcelain that has been fired. The high-temperature fast firing at 1100~1260℃ makes the pigment penetrate into the glaze, and the glaze is closed after cooling. In-glaze color tableware can also prevent the precipitation of heavy metals in the "color", which is healthy and environmentally friendly. Generally, it is produced more as tableware. Because the cost is relatively expensive, this process is not used for general crafts.
3) On-glaze color is made by firing white-glazed porcelain, painting on the white glaze, and then firing it at 600～900℃. The overglaze color has a wide variety of color materials and rich colors. However, "color" adheres to the ceramic surface and has a raised feeling when touched by hand, so it is easy to wear, easy to be corroded by acid and alkali, and easy to fade. The heavy metals used in tableware "color" are easy to precipitate, which is not good for health.
In summary, to choose a safe ceramic tableware, you can refer to the following suggestions:
1) Choose ceramic tableware fired at high temperature (greater than 1000℃);
2) Those who do not pursue patterns and colors should choose white porcelain tableware without decoration;
3) If you pursue patterns and colors, it is best to choose underglaze and inglaze ceramic tableware;
4) Avoid choosing ceramic tableware with overglaze colors (the touch is raised).